Brake accelerator



w. HILDEBRAND BRAKE ACCELERATO R July 17, 1923; 1,461,846

Filed July 21 1920 I le I I al/1,10,, WIIIIIIA Patented July 17, 1923.

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WILHELM nr innnnann, or rrcnrnnsnne, BERLIN, GERMANY, AssIcnoR To'KNoRrt-T q BRAKE accnrnnnron.

' Application filed Jilly 21,

To all whom it may concern I Be it known that I, WILHnLM HILDE- BRAND, a citizen of the GermanRepublic,

residing at New Bahnhofstrasse 9-17.

Lichtenberg, Berlin, Germany, have invented certain new and useful Improvements in Brake Accelerators (forwhich "I have received patents as follows: Germany, No.

dated 18th Austria, No. 76,990, 12th December, 1916; Hungary, No. 72,329,.13th December, 1916; Sweden No. 44,065pdated 14th December, 1916;S witzer1and, No. 75,610, dated 12th December, 1916; and Finland, No; 7,806, dated 21st June, 1919), oiiqwhich the tol lowing is a specification.

, In brake accelerators as hitherto con structed. by which on the initiation of an,

application of the brakes air from the train pipe is caused to pass into a transfercharnber, the pressure in this latter is relieved immediately the triple valve or brake accelerator returns to the brake off position one hand this causes far too great a volume I of air to be consumed, and on the other hand the stages of the application of the brake, corresponding to the greater drop in the pressure in the train pipe, are too great. This becomes specially manifest in such brakes in which it is possible to take the brake partially ofi by any of the well known means, as at every increase in the action of the brake, which is preceded by a partial taking off of the brake, the renewed action of the transfer chambers is too great.

This disadvantage is obviated according to the present invention by controlling the connection of the train pipe with the transfer chamber by a valve which is acted upon by the pressure in the brake cylinder and which is only opened again when the action of the brake cylinderceases, and therefore tiger the brake has been completely taken 0 A diagrammatic view of a constructional example designed for a single chamber brake is shown in the drawing, in which t Figure 1 shows the brake in the brake olf position and December, 1915 1920. .Seria1No.398,039.

Figure 2 the same in the brake on poi sition, i i v y The "compressed air admitted to the train pipe L passes therefrom through the branch pipe Z into the chamber I of the triple valve S, and forcesthe piston a together with the slide valve 6 into the extremeright handposition, then passes onxthrlough the groove made in the usual way into the chains ber II and the auxiliary air reservoir II connected therewith; The brake cylinder -i B is connected to the triple valvebythe pipe g a nd this latter communicates, inithe position shownin Figure 1', through the re 'cess in the slide valve bwiththe pipe 7:

cation with the pipe f through the pipe (4 and the recess in the slidevalve. The emergency apparatus D contains the emergency valveic, and also the differential piston d 03 connected thereto. 1 This latter divides the casing ofthe emergency device intothe chambers III, IV and V. The chamber III is connected by the pipe h with the,

brake cylinder, the chamber IV with the outer air by the passages made in the casing, and the chamber V as has already been stated above, withthetransfer'chamber K. The piston z' of the br-akecylinder is connected in the well known way with the brake gear of the vehicle,

lVhen an application of the brakes is initiated by letting air escape from the continuous brake or train pipe L, the pressure in thechamber I of the triple valve decreases, so that the piston a together with the slide valve 7) can move over into the brake on position shown in Figure 2. In this position the branch pipe Z leading from the brake or train pipe I1 is connected by the recess in the slide valve 7) to the pipe 6, the chamber V and the chamber K. Consequently the air from the train pipe at once fills the chamber K, whereby the transmission of the action of the brake to the following brake devices is accelerated in the well known way. At the same time compressed air passes out of the auxiliary air the brake cylinder 13 and drives the piston a' towards the right. When this takes place the pipe h leading to the chambe-rIII isqexposed; so that the compressed air passing into the brake cylinder, also passes under the piston d}. I Immediately the pressurev has risen sufli'cientl'y iii the chamber III, the differential piston al 03 becomes raised and closes the valve 0, as shown in FigureQ. As the area of the piston d is a multiple ofthe area of the piston (5 the diiferential piston 61 d andconsequently also the valve 0 Willhreinai n in the position shown in FigureQ, so long as the piston of the brake cylinder iremains in the brake on position, therefore also so long as the brakes are not entirely taken off. It'is at the" same time" convenient, but not essentia'l,- that'the admission of air to the branch pip? I I 72; should be controlled by the piston i. the dimensions of the differential piston 03 d are correct it also suffices ifor the pipe It to communicate direct with the pipe 9. The equalization between the air pressure in" the brake or train pipe L and the transfer chamber K takes place very rapidly, whereas the pressure in" the brake cylinder increases compatatively slowly. 7 If the brake cylinder and the pipe 6 be completely emptied of air,- the air also es-q capes out of the pipe band the chamber III. The" compressed air still enclosed in the a chamber K then-forces the piston (Z downwards and opens the valve 0, so that the chamber K is now also completely emptied of air through the pipes e and f.

.In the same Way the apparatus may also be employed "for other brakes, particularly for two-chamber compressed air brakes or for vacuum brakes. In such cases it is only necessary that the difference of pressure required for the action of the brake in twochamber compressed air brakes or vacuum brakes should be suitably employed 'for closing the emergency valve.

; that I ClLlIIl and desire to secure by Let:

ters Patent of the United States is p 1; Ina brake accelerator, a transfer chain" her to receive air from. the train pipe when an application of the brake is initiated, a brake cylinder, a de-aer'a'ting pipe normally in connection with said transfer chamber and with said-brakecylinder, means for cutting off said connection with said de-J aerating pipe, and a valve for controlling" the connection of the train pipe with sai transfer chamber said valve bei-ngin turn controlled byfiuid' uncler'pressure flowing directly from said brake cylinder; p 2. In a brake accelerating apparatus for trains of vehicles, a train pipe, an expansionchaniber,-an outlet pipe communicat- 'WILHELMI HILDEBRAND. 

